Electrical augmentation of a gas turbine engine

Abstract

One aspect is an electrical augmentation system for a gas turbine engine. The electrical augmentation system includes an electric motor operably coupled to a shaft of the gas turbine engine, and an energy storage device operable to provide a temporary increased current source to the electric motor. The electrical augmentation system includes a control system having a torque demand anticipation circuit operable to determine an anticipated torque increase condition for the gas turbine engine. Based on the anticipated torque increase condition, the torque demand anticipation circuit commands a temporary torque increase by the electric motor using the energy storage device.

What is claimed is: 
     
       1. An electrical augmentation system for a gas turbine engine, the electrical augmentation system comprising:
 an electric motor operably coupled to a shaft of the gas turbine engine; 
 a current source operable to provide current to the electric motor during normal operation of the gas turbine engine; 
 an energy storage device operable to provide a temporary increased current to the electric motor; and 
 a control system comprising a torque demand anticipation circuit operable to determine that an anticipated torque increase condition for the gas turbine engine has been reached and, in response to determining that the anticipated torque increase condition has been reached, commanding a temporary torque increase by the electric motor using current from the energy storage device. 
 
     
     
       2. The electrical augmentation system according to  claim 1 , wherein the current source is an electrical generator driven by the gas turbine engine and operable to provide an electrical current to the electric motor to negate motor inertia of the electric motor. 
     
     
       3. The electrical augmentation system according to  claim 2 , wherein the energy storage device is charged by the electrical generator. 
     
     
       4. The electrical augmentation system according to  claim 1 , wherein the electric motor is a starter motor for the gas turbine engine and is not configurable as a generator during operation of the gas turbine engine. 
     
     
       5. The electrical augmentation system according to  claim 1 , wherein the torque demand anticipation circuit is further operable to:
 receive input from an automated control that defines a planned sequence of operating conditions over a period of time; 
 identify within the planned sequence a transient condition associated with a need to accelerate the gas turbine engine; and 
 schedule the anticipated torque increase condition based on an expected time of reaching the transient condition associated with the need to accelerate the gas turbine engine. 
 
     
     
       6. The electrical augmentation system according to  claim 1 , wherein the energy storage device is a battery or a super capacitor. 
     
     
       7. A method of electrical augmentation for a gas turbine engine, the method comprising:
 providing current to an electric motor from a current source during normal operation of the gas turbine engine; 
 monitoring a plurality of system state values defining operating conditions of the gas turbine engine over a period of time; 
 determining whether an anticipated torque increase condition for the gas turbine engine has been reached; and 
 based on reaching the anticipated torque increase condition, commanding an electric motor to provide a temporary torque increase to the gas turbine engine using an energy storage device to provide a temporary increased current to the electric motor. 
 
     
     
       8. The method according to  claim 7 , wherein the current source is an electrical generator driven by the gas turbine engine and providing current to an electric motor from a current source during normal operation includes regulating the current provided from the electrical generator to the electric motor to negate motor inertia of the electric motor. 
     
     
       9. The method according to  claim 8 , further comprising: charging the energy storage device by the electrical generator. 
     
     
       10. The method according to  claim 7 , wherein the electric motor is a starter motor for the gas turbine engine and is not configurable as a generator during operation of the gas turbine engine. 
     
     
       11. The method according to  claim 7 , further comprising:
 receiving input from an automated control that defines a planned sequence of operating conditions over a period of time; 
 identifying within the planned sequence a transient condition associated with a need to accelerate the gas turbine engine; and 
 scheduling the anticipated torque increase condition based on an expected time of reaching the transient condition associated with the need to accelerate the gas turbine engine. 
 
     
     
       12. A gas turbine engine comprising:
 a first shaft upon which a gas generator turbine and a gas generator compressor are mounted, the first shaft operably coupled to an electric motor of an electrical augmentation system; 
 a heat source disposed between the gas generator turbine and the gas generator compressor; and 
 a power turbine coupled to a second shaft to drive a load and an electrical generator of the electrical augmentation system, the electrical generator being operable to provide current to the electric motor during normal operation of the gas turbine engine, the second shaft arranged coaxially with respect to the first shaft; 
 wherein the electrical augmentation system further comprises:
 an energy storage device operable to be charged by the electrical generator and to provide a temporary increased current to the electric motor; and 
 a control system comprising a torque demand anticipation circuit operable to determine an anticipated torque increase condition for the gas turbine engine has been reached and, in response to determining that the anticipated torque increase condition has been reached, commanding a temporary torque increase by the electric motor using current supplied from the energy storage device. 
 
 
     
     
       13. The gas turbine engine according to  claim 12 , wherein the electrical generator is operable to provide an electrical current to negate motor inertia of the electric motor. 
     
     
       14. The gas turbine engine according to  claim 12 , wherein the electric motor is a starter motor for the gas turbine engine and is not configurable as a generator during operation of the gas turbine engine. 
     
     
       15. The gas turbine engine according to  claim 12 , wherein the torque demand anticipation circuit is further operable to:
 receive input from an automated control that defines a planned sequence of operating conditions over a period of time; 
 identify within the planned sequence a transient condition associated with a need to accelerate the gas turbine engine; and 
 
       schedule the anticipated torque increase condition based on an expected time of reaching the transient condition associated with the need to accelerate the gas turbine engine.